A systematic study on the technique for producing defects on the surface of carbon nanotubes(CNTs)by high-temperature heat treatment is carried out to get an experimental condition that not only can activate CNTs but also has less inference on the structure and performance.Different samples of CNTs are obtained by high-temperature heat treatment in air at different temperatures and for different holding times.The characterization results by scanning electron microscopy(SEM),transmission electron microscopy(TEM),laser Raman spectrometer and infrared spectroscopy show that:high-temperature heat treatment can activate CNTs and produce defects and oxygen-containing hydrophilic groups at the surface and end of the CNTs; the amount of defects and the degree of oxidation in CNTs are affected by the treatment temperature and holding time,and high-temperature heat treatment can activate CNTs at the end preferentially and hold the excellent performance of CNTs.